未清理的MQTT订阅队列

Question

我的发现

根据我的研究，每个队列用于存储发送到每个客户端订阅的主题的消息。例如，当同一个主题（例如1/2/3)被3个不同的客户端（例如A、B、&C_1/2/3)订阅时，将有3个订阅队列（即A_1/2/3、&C_1/2/3)。因此，当消息发送到主题1/2/3时，Artemis将把这些消息放在订阅队列中A_1/2/3、B_1/2/3、C_1/2/3。

实际问题

我们的broker.xml

<configuration xmlns="urn:activemq"
               xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
               xmlns:xi="http://www.w3.org/2001/XInclude"
               xsi:schemaLocation="urn:activemq /schema/artemis-configuration.xsd">

   <core xmlns="urn:activemq:core" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="urn:activemq:core ">

      <name>0.0.0.0</name>
      <security-enabled>true</security-enabled>


      <persistence-enabled>false</persistence-enabled>

      <!-- this could be ASYNCIO, MAPPED, NIO
           ASYNCIO: Linux Libaio
           MAPPED: mmap files
           NIO: Plain Java Files
       -->
      <journal-type>ASYNCIO</journal-type>

      <paging-directory>data/paging</paging-directory>

      <bindings-directory>data/bindings</bindings-directory>

      <journal-directory>data/journal</journal-directory>

      <large-messages-directory>data/large-messages</large-messages-directory>

      <journal-datasync>true</journal-datasync>

      <journal-min-files>2</journal-min-files>

      <journal-pool-files>10</journal-pool-files>

      <journal-file-size>10M</journal-file-size>
      
      <journal-buffer-timeout>64000</journal-buffer-timeout>


      <!--
        When using ASYNCIO, this will determine the writing queue depth for libaio.
       -->
      <journal-max-io>4096</journal-max-io>
      <!--
        You can verify the network health of a particular NIC by specifying the <network-check-NIC> element.
         <network-check-NIC>theNicName</network-check-NIC>
        -->

      <!--
        Use this to use an HTTP server to validate the network
         <network-check-URL-list>http://www.apache.org</network-check-URL-list> -->

      <!-- <network-check-period>10000</network-check-period> -->
      <!-- <network-check-timeout>1000</network-check-timeout> -->

      <!-- this is a comma separated list, no spaces, just DNS or IPs
           it should accept IPV6

           Warning: Make sure you understand your network topology as this is meant to validate if your network is valid.
                    Using IPs that could eventually disappear or be partially visible may defeat the purpose.
                    You can use a list of multiple IPs, and if any successful ping will make the server OK to continue running -->
      <!-- <network-check-list>10.0.0.1</network-check-list> -->

      <!-- use this to customize the ping used for ipv4 addresses -->
      <!-- <network-check-ping-command>ping -c 1 -t %d %s</network-check-ping-command> -->

      <!-- use this to customize the ping used for ipv6 addresses -->
      <!-- <network-check-ping6-command>ping6 -c 1 %2$s</network-check-ping6-command> -->




      <!-- how often we are looking for how many bytes are being used on the disk in ms -->
      <disk-scan-period>5000</disk-scan-period>

      <!-- once the disk hits this limit the system will block, or close the connection in certain protocols
           that won't support flow control. -->
      <max-disk-usage>99</max-disk-usage>

      <!-- should the broker detect dead locks and other issues -->
      <critical-analyzer>true</critical-analyzer>

      <critical-analyzer-timeout>120000</critical-analyzer-timeout>

      <critical-analyzer-check-period>60000</critical-analyzer-check-period>

      <critical-analyzer-policy>HALT</critical-analyzer-policy>
      

      <acceptors>

         <!-- useEpoll means: it will use Netty epoll if you are on a system (Linux) that supports it -->
         <!-- amqpCredits: The number of credits sent to AMQP producers -->
         <!-- amqpLowCredits: The server will send the # credits specified at amqpCredits at this low mark -->

         <!-- Note: If an acceptor needs to be compatible with HornetQ and/or Artemis 1.x clients add
                    "anycastPrefix=jms.queue.;multicastPrefix=jms.topic." to the acceptor url.
                    See https://issues.apache.org/jira/browse/ARTEMIS-1644 for more information. -->

         <!-- MQTT Acceptor -->
         <acceptor name="mqtt">tcp://0.0.0.0:${activeMQ-mqtt-port}?tcpSendBufferSize=1048576;tcpReceiveBufferSize=1048576;protocols=CORE,MQTT;useEpoll=true</acceptor>
         <acceptor name="netty-ssl-acceptor">tcp://0.0.0.0:${activeMQ-mqtts-port}?sslEnabled=true;keyStorePath=${activeMQ-keystore-path};keyStorePassword=${activeMQ-keyStore-password};protocols=CORE,MQTT</acceptor>

      </acceptors>


      <security-settings>
         <security-setting match="#">
            <permission type="createNonDurableQueue" roles="amq"/>
            <permission type="deleteNonDurableQueue" roles="amq"/>
            <permission type="createDurableQueue" roles="amq"/>
            <permission type="deleteDurableQueue" roles="amq"/>
            <permission type="createAddress" roles="amq"/>
            <permission type="deleteAddress" roles="amq"/>
            <permission type="consume" roles="amq"/>
            <permission type="browse" roles="amq"/>
            <permission type="send" roles="amq"/>
            <!-- we need this otherwise ./artemis data imp wouldn't work -->
            <permission type="manage" roles="amq"/>
         </security-setting>
      </security-settings>

      <address-settings>
         <!-- if you define auto-create on certain queues, management has to be auto-create -->
         <address-setting match="activemq.management#">
            <dead-letter-address>DLQ</dead-letter-address>
            <expiry-address>ExpiryQueue</expiry-address>
            <redelivery-delay>0</redelivery-delay>
            <!-- with -1 only the global-max-size is in use for limiting -->
            <max-size-bytes>-1</max-size-bytes>
            <message-counter-history-day-limit>10</message-counter-history-day-limit>
            <address-full-policy>PAGE</address-full-policy>
            <auto-create-queues>true</auto-create-queues>
            <auto-create-addresses>true</auto-create-addresses>
            <auto-create-jms-queues>true</auto-create-jms-queues>
            <auto-create-jms-topics>true</auto-create-jms-topics>
         </address-setting>
         <!--default for catch all-->
         <address-setting match="#">
            <dead-letter-address>DLQ</dead-letter-address>
            <expiry-address>ExpiryQueue</expiry-address>
            <redelivery-delay>0</redelivery-delay>
            <!-- with -1 only the global-max-size is in use for limiting -->
            <max-size-bytes>-1</max-size-bytes>
            <message-counter-history-day-limit>10</message-counter-history-day-limit>
            <address-full-policy>PAGE</address-full-policy>
            <auto-create-queues>true</auto-create-queues>
            <auto-create-addresses>true</auto-create-addresses>
            <auto-create-jms-queues>true</auto-create-jms-queues>
            <auto-create-jms-topics>true</auto-create-jms-topics>
         </address-setting>
      </address-settings>

      <addresses>
         <address name="DLQ">
            <anycast>
               <queue name="DLQ" />
            </anycast>
         </address>
         <address name="ExpiryQueue">
            <anycast>
               <queue name="ExpiryQueue" />
            </anycast>
         </address>

      </addresses>

      <broker-plugins>
         <broker-plugin class-name="org.apache.activemq.artemis.core.server.plugin.impl.LoggingActiveMQServerPlugin">
            <property key="LOG_ALL_EVENTS" value="true"/>
            <property key="LOG_CONNECTION_EVENTS" value="true"/>
            <property key="LOG_SESSION_EVENTS" value="true"/>
            <property key="LOG_CONSUMER_EVENTS" value="true"/>
            <property key="LOG_DELIVERING_EVENTS" value="true"/>
            <property key="LOG_SENDING_EVENTS" value="true"/>
            <property key="LOG_INTERNAL_EVENTS" value="true"/>
         </broker-plugin>
      </broker-plugins>
   </core>
</configuration>

Answer 1

当订阅完成时，它实际上是由订阅服务器来删除它的订阅。换句话说，MQTT客户端应该在创建新的订阅服务器之前取消对现有订阅服务器的订阅。代理无法知道订阅服务器是否计划稍后重新连接以从其订阅中获取消息。

如果确实希望代理删除订阅队列，可以使用以下地址设置：

• :必须true.
• :这是从最后一个使用者断开连接到代理删除订阅队列的延迟（毫秒）。
• :必须为-1，才能忽略订阅队列中的任何消息。